The present invention relates to IC cards, and more specifically to an IC card including an integrated circuit (IC) for performing data transmission.
Some IC cards perform data transmission with a terminal electrically connected to a control portion, while others perform data transmission in a non-contact state. In the non-contact type IC card, power is obtained form a radio wave from an antenna for transmission of information stored in the internal non-volatile memory. Such non-contact type IC card is used for a gate of the ski lift, gate at the station and sorting of parcels and the like.
FIG. 6 is a schematic diagram showing a structure of a conventional non-contact type IC card. As shown in FIG. 6, a conventional non-contact type IC card 1 includes an IC 101 and an antenna 102 connected to IC 101. IC 101 and antenna 102 are contained in IC card 1. IC card 1 is generally formed of an insulating material such as polyester or vinyl chloride. The non-contact type IC card as shown in FIG. 6 is generally referred to as an and antenna 102 are both conductive and have lower resistance as compared with IC card 1. Thus, when static electricity or the like is externally transferred to IC card 1, discharge current of the static electricity may flow into IC 101 and antenna 102. If the discharge current of static electricity flows into IC 101 and antenna 102, electrostatic breakdown of IC 101 is caused. As a result, breakdown and malfunction of the entire portion of IC card 1 are disadvantageously caused.
More specifically, as shown in FIG. 7, for example, assume that a portion A of IC card 1 is held by a person charged with static electricity when a portion B is grounded. In this case, discharge current of static electricity first flows into that portion of insulating material at the surface of IC card 1 which is positioned at A, and then into IC 101 and antenna 102 of IC card 1 for being discharged from portion B. This may lead to a problem associated with breakdown of the entire card including IC 101 and antenna 102. Such problem also arises, for example, when a ground rod is brought closer to the electrically charged card.
The present invention is made to solve the aforementioned problem, and it is an object to provide an IC card capable of effectively preventing electrostatic breakdown of an IC even when the IC card is charged with static electricity.
An IC card according to the present invention includes an integrated circuit (IC) and is characterized in that a portion thereof is provided with a discharging member of a non-insulator. Such provision of the discharging member of the non-insulator enables discharge current of static electricity to be discharged through the discharging member, thereby effectively preventing the discharge current from flowing into the integrated circuit even when the IC card is charged with static electricity. Thus, electrostatic breakdown of the integrated circuit is prevented even when the IC card is charged with static electricity, so that breakdown or malfunction of the entire IC card is prevented. In the above structure, the discharging member may be provided in a prescribed region other than that where the integrated circuit of the IC card is arranged. In the above structure, the discharging member may include a metal layer formed on an inner surface of a through hole in the IC card. In the above structure, the discharging member may have a thickness which is at least greater than those of the antenna and integrated circuit (IC). In the above structure, the discharging member may be provided at a periphery of the IC card. In the above structure, the discharging member may be provided on the surface of the IC card in a mesh like manner. More preferably, in the above structure, the discharging member is provided to surround the integrated circuit. Such provision of the discharging member to surround the integrated circuit also enables the static electricity to be discharged through the discharging member surrounding the integrated circuit when the IC card is charged with the static electricity, so that the discharge current is prevented from flowing into the integrated circuit. In other words, the discharging member functions as a shield for protecting the integrated circuit. More preferably, in any of the above mentioned structures, the non-insulator forming the discharging member may be any of conductive rubber, conductive resin, conductive coating and metal.